1. Field of the Invention
The present invention relates to a system for detecting abnormal operation of an electronic circuit and, more particularly, to an abnormal operation detection system suited to detect abnormal operation of a large-scale integrated circuit device such as an FPGA or an ASIC.
2. Description of the Related Art
In a large-scale integrated circuit device such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), a design problem can lead to a fatal problem that causes the circuit to hang up and forces the system to stop. Furthermore, as device miniaturization progresses, there can arise the possibility that, even if there is no design problem, the circuit may malfunction or a deadlock may occur due to a soft error such as the alteration of device logic or bit flipping caused by cosmic rays reaching the earth, and this can result in a fatal problem such as a system stoppage.
In the patent documents 1 to 3 listed below, it is described that abnormal operation is detected by monitoring the power consumption of a monitored unit or device. However, generally, the power consumption of a monitored device during normal operation changes with its internal operating state, but none of these patent documents take account of such factors as the state of the internal state machine of the monitored device, the ambient temperature at which the device is actually operating, and variations among individual devices.
In particular, it is desired that the monitoring of a large-scale integrated circuit device, such as an FPGA or an ASIC, that has a state machine construction defined by a plurality of states and a condition for a state transition be performed meticulously so as to match each of the plurality of states that occur as the state machine makes a state transition.
Patent document 1: Japanese Unexamined Patent Publication No. 2004-104879
Patent document 2: Japanese Unexamined Patent Publication No. 2001-287355
Patent document 3: Japanese Unexamined Patent Publication No. 2001-74804